Page:Popular Science Monthly Volume 46.djvu/846

826 practice, were accustomed to use their surplus catch as manure, placing a thousand fish to the acre. The Towsers of that day evidently gave trouble, as would appear from the following quaint and amusing town law of Ipswich passed in May, 1644:

"It is ordered that all Doggs for the space of three weeks after the publishing hereof shall have one Legg Tyed up. If such a Dogg should break loose and be founde in any Cornefielde doing any harme, the Owner of the Dogg shall pay the Damage. If a man refuse to tye up his Doggs legg and he be found scraping up Fish in the Cornefielde, the Owner shall pay 12s., besides whatever Damage the Dogg doth."

Of the shad, man, without doubt, is the greatest agent of destruction, although his wasting effort is exerted only within the borders of his own domain; but beyond, in the open sea, the ranks of the migrating horde are thinned by the shark, porpoise, and dogfish, the seal, otter, and salmon, and, most destructive of all, the bluefish. This dread sea butcher works terrible havoc among all neighboring fish not larger than himself, and in the shoals of shad, like those of the menhaden, he revels in slaughter. His opportunity, however, is brief, and perhaps not frequently exercised upon the incoming fish, his earliest appearance in our latitude being usually later than that of the shad. Along New Jersey, however, there have been instances of shoals of shad being driven upon the shore by his murderous onslaughts, the bluefish being a creature that often seems to chop, maim, and destroy for mere amusement.

The shad, after its entrance into our rivers, eats nothing, the one all-dominating impulse being that of the maintenance of its species; for that it braves every danger and endures every hardship. It presses on, sparing no exertion to attain its goal; if it halts or retreats, it is because the temperature of the river current has fallen too low for the development of its ova. It manifests an acute discrimination of gradations of heat, recognizing promptly differences of a degree or even less. In spawning it seeks a temperature of about 60°, and usually deposits its eggs near sunset, when the water is warmest, the place chosen being often the downstream edge of wide flats, over which the gently flowing current becomes heated to the requisite point. That current thenceforward becomes the foster mother of the deposited ova, its suspended oxygen ever vivifying the slowly developing germ, and, thus cared for, the abandoned and apparently neglected waif waxes apace. As soon as capable of independent movement, the tiny fish, scarce half an inch long, with its yolk sac as yet unabsorbed, strikes out for the deeper portions of the river, its instinct possibly teaching it that to tarry is destruction, for there it would become the assured prey of the minnows, killifish, and other small fry that